1. Prepare the Beef: In a medium bowl, toss the beef tips with 1 tablespoon of soy sauce and the cornstarch until well coated. This step helps tenderize the beef and creates a slight crust when cooked. Set aside while you prepare other ingredients.

2. Cook the Rice Noodles: Bring a pot of water to a boil. Add the rice noodles and cook according to package directions, usually 3-5 minutes, until tender but still firm (al dente). Drain immediately and rinse with cold water to prevent sticking. Drizzle with 1 teaspoon of sesame oil and toss gently to coat.

3. Saute Aromatics and Beef: Heat the vegetable oil in a large skillet or wok over high heat until shimmering. Add the beef in a single layer and cook for 2-3 minutes per side until browned. You don’t need to cook it through at this stage. Remove the beef from the skillet and set aside. Add the sliced onion to the same skillet and stir-fry for 2 minutes until slightly softened. Add the minced garlic and grated ginger and cook for another minute until fragrant.

4. Add Vegetables and Sauce: Add the sliced red bell pepper and broccoli florets to the skillet. Stir-fry for 3-4 minutes until the vegetables are crisp-tender. While the vegetables cook, whisk together the beef broth, remaining 1 tablespoon soy sauce, oyster sauce (if using), and sugar in a small bowl.

5. Combine Everything: Return the cooked beef to the skillet with the vegetables. Pour the sauce mixture over everything. Bring to a simmer and cook for 1-2 minutes, stirring constantly, until the sauce thickens slightly and coats the beef and vegetables.

6. Toss with Noodles: Add the cooked rice noodles to the skillet. Use tongs to gently toss everything together, ensuring the noodles are evenly coated with the sauce and all ingredients are well combined and heated through.

7. Serve Immediately: Garnish generously with sliced green onions and toasted sesame seeds. Serve hot and enjoy your delicious homemade stir fry!